Device for reducing damage due to head slap within a hard disk drive

ABSTRACT

A hard disk drive assembly that includes a device for limiting a movement of a head of a head gimbal assembly from a surface of a disk. The head is coupled to the disk and attached to a suspension of the head gimbal assembly. The invented device limits a distance that the head can move away from a surface of the disk. Limiting the distance that the head can move away from the surface of the disk, may reduce the impact force associated with the head slapping the disk, which may reduce damage associated with head slapping.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a device which limits a movementof a head within a hard disk drive assembly.

[0003] 2. Background Information

[0004] Hard disk drives contain transducers that are magneticallycoupled to one or more rotating disks. The transducers can write andread information by magnetizing the disk surface and sensing themagnetic field that flows from the disks, respectively. The transducersare integrated into a head that is mounted to a suspension. The head andsuspension are typically referred to as a head gimbal assembly (HGA).

[0005] The HGA's of a hard disk drive are mounted to an actuator armthat is pivotally connected to a base plate of the drive. The drive mayfurther include a voice coil motor that rotates the actuator arm andmoves the heads across the surfaces of the disks.

[0006] Each head has an air bearing surface which cooperates with an airflow generated by the rotation of the disks to create an air bearingpressure between the transducers and the disk surfaces, while the disksare rotating. The air bearing pressure allows the head to fly over arotating disk at a certain nominal fly height to prevent mechanical wearbetween the disks and the heads.

[0007] The heads are essentially suspended from the actuator arm aboveor below the surfaces of disks. Any shock or vibration loads essentiallyperpendicular to the disk surfaces may cause the heads to strike or“slap” the disks. Head slapping may damage both the heads and the disks.

[0008] Head slapping typically occurs when the shock load is greatenough to cause the head to “separate” away from the disk surface. Thelargest head slapping forces are typically associated with the top andbottom HGAs located adjacent to the base plate and the cover plate ofthe disk drive, since there is a relatively large amount of spacebetween the plates and the top and bottom HGAs. The large spaces allowthe heads to move away from the disk surfaces and then slap back ontothe disks.

[0009] The force required to create a head slap can be increased byreducing the length of the suspension and/or reducing the mass of thehead. Reducing the length of the arm and/or the mass may create anundesirable change in the mechanical characteristic of the HGA. It wouldbe desirable to provide a hard disk drive that limits the movement of anHGA within the drive.

SUMMARY OF THE INVENTION

[0010] The present invention comprises a hard disk drive assembly thatincludes a device for limiting a movement of a head of a head gimbalassembly from a surface of a disk. The head is coupled to the disk andattached to a suspension of the head gimbal assembly. The inventeddevice limits a distance that the head can move away from a surface ofthe disk. By limiting the distance that the head can move away from thesurface of the disk, the impact force associated with the head slappingthe disk may be reduced. This may reduce damage to the head, the disk,or both.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a top view of a hard disk drive assembly of the presentinvention;

[0012]FIG. 2 is a side sectional view of the disk drive assembly;

[0013]FIG. 3 is a side sectional view showing an alternate embodiment ofthe invented disk drive assembly; and

[0014]FIG. 4 is a side sectional view showing another alternateembodiment of the disk drive assembly.

DETAILED DESCRIPTION

[0015] The present invention comprises a hard disk drive assembly thatincludes a device for limiting a movement of a head of a head gimbalassembly from a surface of a disk. The head is coupled to the disk andattached to a suspension of the head gimbal assembly. The device of thepresent invention limits a distance that the head can move away from asurface of the disk. By limiting the distance that the head can moveaway from the surface of the disk, the impact force associated with thehead slapping the disk may be reduced, to reduce damage associated withhead slapping.

[0016] One embodiment of the present invention is an extended distal endof an actuator arm beam. The extended distal end of the actuator armbeam extends above a portion of the suspension to limit the distancethat the head can move away from the surface of the disk. In anotherembodiment, the present invention is a limiter plate that limits amovement of the head from the surface of the disk. By limiting thedistance that the head can move away from the surface of the disk, theimpact force associated with the head slapping the disk may be reduced.This may reduce damage to the head, the disk, or both.

[0017] Referring to the drawings more particularly by reference numbers,FIGS. 1 and 2 show an embodiment of a hard disk drive assembly 10 of thepresent invention. The disk drive assembly 10 may include one or moredisks 12 that are rotated by a spin motor 14. The spin motor 14 may bemounted to a base plate 16. Each disk 12 may have a top surface 18 andan opposite bottom surface 19.

[0018] A plurality of heads 20 may be magnetically coupled to the disks12. The heads 20 may each contain one or more transducers that areelectrically connected to electronic circuitry (both not shown) of thedisk drive. The circuitry and transducers can write and read informationby magnetizing and sensing the magnetic field of the disks 12,respectively.

[0019] Each head 20 is mounted to a suspension 22. The head 20 andsuspension 22 are commonly referred to as a head gimbal assembly (HGA)24. Typically there is an HGA 24 associated with each surface 18 and 19of a disk 12. The HGAs 24 are mounted to beams 26 of an actuator arm 28that is pivotally mounted to the base plate 16.

[0020] The suspensions 22 are typically attached to the actuator armbeams 26 with swage plates 30. The swage plates 30 extend throughcorresponding apertures 31 in the beams 26 and the suspensions 22. Eachsuspension 22 may have an elbow 32 so that the arm 22 is inclined towardthe surface 18 of a corresponding disk 12.

[0021] The actuator arm 28 may be coupled to a voice coil motor 34 thatcan be actuated to rotate the arm 28 and move the heads 20 across thesurfaces 18 and 19 of the disks 12. The voice coil motor 34 comprises avoice coil 36 that is coupled to the actuator arm 28, and a magnetassembly 38 that is coupled to the voice coil 36 and attached to thebase plate 16. The disks 12, HGAs 24, actuator arm 28 and voice coilmotor 34 are enclosed by a cover 40 that is attached to the base plate16.

[0022] It is desirable to prevent movement of the heads 20 along a “zdirection”, for example, in a direction that is generally perpendicularto the surfaces 18,19 of the disks 12, as indicated by the arrow shownin FIG. 2. This movement may be induced by external shock or vibrationloads. Z movement of the heads 20 away from the disk surfaces may resultin a counter movement back into the disks 12. The impact force of theheads 20 striking the disk surfaces 18 and 19 may cause damage to theheads 20, the disks 12, or both.

[0023] Each actuator arm beam 26 may have an arm extension 42 thatextends beyond the elbow 32 of the suspension 22. The arm extension 42limits the movement of the head 20 away from the disk surface. Bylimiting the generally perpendicular movement Z of the suspension 22 andhead 20 away from the disk surface, the arm extension 42 limits themomentum and corresponding impact force of the head 20 as it slaps thedisk 12. FIG. 3 shows another embodiment of the present inventionwherein the disk drive assembly includes a limiter plate 42A that isattached to the suspension 22 and the actuator arm beam 26. The limiterplate 42A includes an outwardly projecting tab 44 that extends along thesuspension 22. Preferably, the tab 44 may be inclined toward thesuspension 22 to minimize a gap 46 between the tab 44 and arm 22. Thegap 46 should be sufficiently wide to account for manufacturingtolerances and insure that the tab 44 does not inadvertently exertpressure against the suspension 22 during the operation of the drive.The gap 46 should also be sufficiently narrow to prevent undesirablemovement of the head 20 away from the disk surface 18, 18 adjacent tothe head 20.

[0024]FIG. 4 shows an alternative embodiment of the limiter plate 42Bthat is attached to an end surface 48 of the actuator arm beam 26. Thealternative embodiment of the limiter plate 42B has a lower heightprofile than the first embodiment 42A, shown in FIG. 3. The alternativeembodiment of the limiter plate 42B may have a tapered end section 50.Preferably, the end section 50 has a slanted bottom surface 52 thatextends generally parallel to the suspension 22, when the limiter plate42B is attached to the end surface 48.

[0025] When the drive is subjected to a shock load, such as a shock loadgenerally perpendicular to the disks 12 along the Z direction, thecorresponding forces can cause both the suspension 22 and limiter plate42A or 42B to move away from the disks 12 or toward the disks. Thestiffness of the limiter plate 42A or 42B may be greater than thestiffness of the suspension 22 so that the plate 42A or 42B does notdeflect in an upward or downward direction as much as the arm 22 wouldmove without a limiter. The smaller plate deflection will thereforelimit the movement of the arm 22 away from the disk. The limiter plate42A or 42B may also have a mechanical transfer function that insuresthat the plate does not move in phase with the suspension 22 duringshock or vibrational loading.

[0026] While certain exemplary embodiments have been described and shownin the accompanying drawings, it is to be understood that suchembodiments are merely illustrative of and not restrictive on the broadinvention, and that this invention not be limited to the specificconstructions and arrangements shown and described, since various othermodifications may occur to those ordinarily skilled in the art.

What is claimed is:
 1. A hard disk drive assembly, comprising: a diskthat has a surface; a spin motor that rotates said disk; a head that iscoupled to said disk surface; a suspension that is attached to saidhead, said suspension having an elbow; an actuator arm which has a beamthat is attached to said suspension, said beam having a distal end thatextends beyond said elbow of said suspension to limit a movement of saidhead; and a voice coil motor that is coupled to said actuator arm andmoves said head across said surface of said disk.
 2. The hard disk driveof claim 1 wherein the distal end of said suspension limits a distancethat said head can move away from the surface of said disk.
 3. A harddisk drive assembly, comprising: a disk that has a surface; a spin motorthat rotates said disk; a head that is coupled to said disk surface; asuspension that is attached to said head; an actuator arm which has abeam that is attached to said suspension; a voice coil motor that iscoupled to said actuator arm and moves said head across said surface ofsaid disk; and a limiter plate that is attached to said suspension andsaid actuator arm, said limiter plate limits a movement of said head. 4.The hard disk drive of claim 3 wherein said limiter plate limits adistance that said head can move away from the surface of said disk. 5.The hard disk drive of claim 4, wherein said limiter plate is benttoward said suspension.
 6. The hard disk drive of claim 5 wherein saidlimiter plate further comprises a tab that extends above saidsuspension.
 7. The hard disk drive of claim 6 wherein the tab of saidlimiter plate extends generally parallel to said suspension, said tabextending generally parallel to said suspension to limit a distance thatsaid head can move away from the surface of said disk.
 8. The hard diskdrive of claim 6 wherein the tab of said limiter plate extends generallyparallel to said suspension to limit a distance that said head can moveaway from the surface of said disk to limit an impact force as said headstrikes said disk.
 9. The hard disk drive of claim 3, further comprisinga swage plate that attaches said suspension and said limiter plate tosaid actuator arm.
 10. A hard disk drive assembly, comprising: a diskthat has a surface; a spin motor that rotates said disk; a head that iscoupled to said disk surface; a suspension that is attached to saidhead; an actuator arm which has a beam that is attached to saidsuspension, said beam having an end surface; a voice coil motor that iscoupled to said actuator arm and moves said head across said surface ofsaid disk; and a limiter plate that is attached to said end surface ofsaid actuator arm, said limiter plate limits a movement of said head.11. The hard disk drive of claim 10 wherein said limiter plate extendsgenerally parallel to said suspension to limit a distance that said headcan move away from the surface of said disk.
 12. The hard disk drive ofclaim 11 wherein said limiter plate extends generally parallel to saidsuspension to limit a distance that said head can move away from thesurface of said disk to limit an impact force as said head strikes saiddisk.
 13. The hard disk drive of claim 10, wherein said limiter plate isbent toward said suspension.